Antigen detection assay in contrast to conventional serological test, detects disease status and not the host antibody response to the disease etiological agent. It can therefore be used for both diagnosis and disease treatment follow-up purposes. Antigen detection assay has been successfully used for the diagnosis of different infectious diseases including sore throat caused by Streptococcus pyogenes, hepatitis, pneumonia caused by Streptococcus pneumoniae or Legionella pneumophilla, and amoebiasis. Although antigen detection assay has the potential to quickly diagnose active visceral leishmaniasis (VL), paradoxically this test has not yet been fully developed for this serious disease. Using the ultra-sensitive mass spectrometry technology we have recently identified proteins from the etiological agent of VL (Leishmania infantum) in the patients'urine. These findings constitute the foundation of the present project, which aims to use these unique proteins as well as other to be identified to develop a highly sensitive and specific antigen detection assay for the accurate diagnosis of active VL. PUBLIC HEALTH RELEVANCE: This SBIR project aims to develop an antigen detection assay for the diagnosis of visceral leishmaniasis (VL). The general foundation of the proposal is based on the proponent's group finding of Leishmania infantum proteins in the urine of patients with visceral leishmaniasis (VL). Because L. infantum is the etiological agent of VL these findings strongly support the development of an antigen detection assay for the diagnosis this serious disease.